1. Field of the Invention
Tubes consistent with what is disclosed herein relate to a super miniature X-ray tube using a nano material field emitter.
2. Description of the Related Art
The cancer management options include, mainly, surgery (physical option) and chemotherapy (biological option).
The surgery generally removes tumor from a target area completely, but may involve intrusion on a patient's body such as considerable physical wound and damages to the functional organs. Besides, this mechanical process may have remaining cancer cell after the surgery.
The chemotherapy injects a substance fatally reactant exclusively to the cancer cells to kill the cancer cells, but generally, this treatment results in painful side effects and does not guarantee complete cure from the cancer, although this may delay the growth and spread of the cancer by a certain period of time.
Radiation therapy mainly induces killing of cancerous cells having faster cycles of cell division than normal cells, by focusing radioactive energy to a target are of the body.
According to the previous clinical tests, radiation therapy has been particularly effective in attacking the body area to where access by surgery is not allowed, showing noticeable treatment. At the same time, due to minimized intrusion on the human body and no damages to the organs, this treatment can keep body functions intact.
The radiation therapy may be generally categorized into two therapies: i) radiotherapy (or teletherapy) in which a relatively large sized accelerator or radioactive isotope irradiates radioactive ray into a patient's body; and ii) brachytherapy in which a radiation source is installed near the cancer cell to locally treat the cancer.
Since the external radiotherapy irradiates radioactive ray also to the healthy tissues around the cancer cells, this type of therapy involves damage to the healthy tissues. However, the brachytherapy can minimize the damage to the normal cells. The brachytherapy also has a relatively high dose rate and thus takes a relatively short time for treatment.
Generally, the brachytherapy utilizes radioactive isotope as the source of radiation.
Although the radioactive isotopes are advantageous particularly in terms of compactness, it has some disadvantages, which are: i) continuous generation of radioactive rays keeps a person handling the radioactive isotope at a risky exposure to the radioactive rays; ii) the short half life period requires supply of radioactive source on a regular basis, and strict requirements for storage, maintenance and disposal of the radioactive wastes.
In order to overcome the abovementioned disadvantages, a miniature X-ray tube, which is small enough to be inserted in the human body, has been developed.
The X-ray tube generates X-ray only in response to an input of electric current, and accordingly, neither a doctor nor a patient is exposed to the radioactive rays unnecessarily. Additionally, because it is possible to adjust the generated radioactive energy and the rem dose distribution easily, the effective cancer treatment based on appropriately-regulated rem dose distribution is provided, and because the radioactive rays are generated only in response to the electric current, strict requirements for production, storage, maintenance, or disposal of waste, are not necessary.
The currently-available X-ray tube generally employs a metal such as tungsten provided in a filament shape, and therefore, implements a thermionic emission method which forms thermal electrons generated by the heating at high temperature, into beam patterns.
However, in the application of the source of thermal electron beams for use in the miniature X-ray tube, the heat can damage the healthy cells, and the source can not be compact-sized because a small-size source may have the limited density of electric current of the electron beams.
Meanwhile, the recent development in the nano technology has motivated many to study the X-ray tubes utilizing nano material field emitter.
The nano material field emitter, which gives off electron beams in an electroluminescent manner, does not generate heat, requires only a simple powering device, and generates electron beams with the density of electric current a hundred times as large as that of the thermionic emission and thus can generate high power X-ray. Additionally, the cathode can be compact-sized, and it is also easy to adjust the time structure of generating X-rays.
Most currently-available equipments for brachytherapy employ thermionic emission. If a new technology based on the nano material field emitter is utilized, a new type of brachytherapy device, which is compacter and which generates X-rays with higher rem rate compared to the existing devices, could be developed.